The best way to see the changes from the older 21064A to the 21164 is to compare them side-by-side (see table A). By the time you read this, the Alpha 21164A (a technology shrink of the 21164) will be available in systems that run at an unprecedented 433 MHz, and eventually 500 MHz! The 21164A moves from
the 0.5um process of the 21064/21164 to a 0.35um process, which allows for higher clock rates. It also adds 8-bit and 16-bit word-addressing capability, whereas the older CPUs can work only with 32-bit and larger words. And, the core voltage goes down from 3.3 volts (V) (40 watts (W) or more power dissipation on 300-MHz chips) to 2V (20W for 400-MHz+ chips) meaning lower power consumption at higher clock rates.
|TABLE A: Feature Alpha 21064A Alpha 21164 New Benefits|
*Other CPU clock speeds are possible, as defined by individual vendors. By testing chips on a piece-by-piece basis, hardware developers can find those that operate at higher clock rates.